What Happens If You Don't Pay PAYG Instalments?

By Narelle Hartigan, CPAPublished 29 June 20265 min read

The unpaid instalment becomes a tax debt the day after its due date, and general interest charge starts accruing on it daily at 11.43% a year (the rate for the July–September 2026 quarter). No debt collector knocks in week one, but the meter runs until you pay. The good news: the instalment still counts as a credit at assessment even if you pay it late, and payment plans exist. Where instalments fit in the wider system is covered in the PAYG instalments guide.

Jump to:What actually happensThe interest: GIC explainedPayment plansThe credit still appliesFAQ

What actually happens, in order

  1. The due date passes

    The instalment amount is recorded as an outstanding debt on your ATO account. Nothing else changes yet; there is no automatic fine for a late instalment payment itself.

  2. General interest charge starts

    GIC accrues daily on the unpaid balance from the due date, and it compounds: each day's interest joins the base for the next day's.

  3. The ATO follows up

    Reminders come first. A debt left unaddressed can escalate to firmer recovery action, which is why ringing the ATO or setting up a plan early beats silence every time.

  4. Assessment time squares it up

    Your instalment credits are applied against your assessed tax. An unpaid instalment reduces that credit, so the shortfall lands in your final bill, with the GIC on top.

If the real problem is that the instalment is bigger than this year's income justifies, the fix is a variation, not non-payment. That only works on or before the due date, so check how to vary PAYG instalments as soon as a notice looks wrong.

The interest: GIC at 11.43%

The GIC rate is set quarterly. For July–September 2026 it is 11.43% a year, applied as a daily compounding rate of 0.03131507%. Two more things worth knowing: GIC incurred on or after 1 July 2025 is no longer tax deductible, which made late payment materially more expensive, and you can ask the ATO to remit (waive) GIC where circumstances genuinely warrant it.

What a missed $5,000 instalment costs in GIC

90 days latedaily compounding at 11.43% p.a.$143
A full year late$605
Deductible since 1 July 2025$0

Compare that with what the instalment was for in the first place. The PAYG instalment calculator shows the quarterly figure your income actually supports, which is the number worth negotiating around.

Payment plans

If you cannot pay in full, the ATO offers payment plans that spread a tax debt over agreed instalments. Individuals and sole traders can usually set one up in ATO online services through myGov. Two catches: GIC generally keeps accruing on the outstanding balance while a plan runs, and missing a plan payment can cancel the arrangement. A plan stops escalation, not interest.

Ring the ATO before the debt grows rather than after. A taxpayer who calls with a plan is treated very differently from one who goes quiet, and future instalments keep falling due on the normal quarterly dates while you catch up.

The credit still applies at assessment

Whatever happens with timing, instalments never become extra tax. Every dollar you eventually pay is credited against your assessed tax for the year. Pay a quarter late and you still get the credit; you just also owe GIC for the late period. Skip it entirely and the assessment simply collects the same tax without the credit, plus the interest. The system always reconciles to the same total tax, which is why paying on time is purely a cash-flow discipline, and why a first instalment notice is nothing to panic over.

Frequently asked questions

What happens if you don't pay PAYG instalments?
The amount becomes a debt with general interest charge accruing daily from the due date (11.43% p.a. for July-September 2026). The instalment credit is still applied at assessment once paid, but the GIC is a dead cost and is no longer deductible.
Is there a penalty for paying an instalment late?
The cost is GIC rather than a fixed fine. Failure-to-lodge penalties are a separate matter and relate to unlodged activity statements, not late payment of a notice.
Can the ATO waive the interest?
You can request remission of GIC. The ATO considers the circumstances that caused the delay, such as serious illness or natural disaster, and whether you acted to sort the debt promptly.
Do instalments stop if I ignore them?
No. Notices keep issuing each quarter while your last return keeps you over the entry thresholds. Exit happens through a lower lodged return or a withdrawal request when the income activity ceases, not through silence.
Should I pay the instalment or vary it?
If the figure fairly reflects this year, pay it. If income has genuinely dropped, vary on or before the due date. Never vary just to delay payment: a shortfall beyond 15% of actual tax can attract GIC anyway.

Sources

Related resources

Calculator

PAYG Instalment Calculator

The quarterly figure your income supports

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Guide

Varying PAYG Instalments

The before-the-deadline fix for oversized notices

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Guide

PAYG Due Dates

Every 2026-27 deadline and payment method

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Narelle Hartigan
Narelle Hartigan, CPA Verified Expert
Tax Accountant & PAYG Specialist

Narelle Hartigan is a CPA-qualified tax accountant with over a decade of experience in Australian personal taxation and payroll. She founded PAYG Calculator Australia to make tax withholding easy for every Australian worker to understand.

CPABCom (Accounting)
Published: 28 July 2026